1. Field of the Invention
This invention relates to a method and system for concluding the benefits of combining the synergies of waste of a well drilling process with waste of a cement process for the utilization of raw materials and/or thermal energy.
2. Description of the Related Art
U.S. Pat. No. 4,793,423 entitled xe2x80x9cProcess for treating drilled cuttingsxe2x80x9d of Beth C. Knol, granted on Dec. 27th, 1988 relates to processing used drilling liquids, drilled cuttings and salt contaminated soil, etc. in order to produce saline wash water suitable for injecting into a disposal well and size-graded substantially salt-free materials suitable for construction operations or non-hazardous waste disposal.
U.S. Pat. No. 4,809,791 entitled xe2x80x9cRemoval of rock cuttings utilizing an automatically adjustable shaker systemxe2x80x9d of Asadollah Hayatdavoudi, granted on Mar. 7th, 1989 relates to a system for the optimization of particle separation in a shaker system of a well drilling system.
U.S. Pat. No. 4,880,468 entitled xe2x80x9cWaste solidification composition and methodsxe2x80x9d of David A. Bowlin and Michael J. Seuman, granted on Nov. 14th, 1989 relates to a composition for the solidification of waste comprising hydraulic cement, fly ash and fumed silica material and to a method of disposing of waste materials such as drilling muds and cuttings that result from drilling an oil and gas well.
U.S. Pat. No. 4,942,929 entitled xe2x80x9cDisposal and reclamation of drilling wastesxe2x80x9d of Edward Malachosky and Donna M. Lantero, granted on Jul. 24th, 1990 relates to drill cuttings comprising usable gravel, silts, clays and spent drilling fluid, which are recovered and discarded during or after the process of drilling a well by separating construction-grade gravel from drilling fluid and washing the gravel, if necessary, prior to storage or placing it in use as construction material.
U.S. Pat. No. 5,058,679 entitled xe2x80x9cSolidification of water based mudsxe2x80x9d of Arthur H. Hale and Kenneth M. Cowan, granted on Oct. 22nd, 1991 relates to a drilling mud, which is converted in-situ to a cement by addition of blast furnace slag.
In U.S. Patent No. 5,277,519 entitled xe2x80x9cWell drilling cuttings disposalxe2x80x9d of James J. W. Nahm, granted on Jan. 11th, 1994 drilled cuttings are eliminated by solidification by drilling with a drilling fluid containing blast furnace slag, thereby producing drilled cuttings and other solid wastes, concentrating the wastes and then solidifying the concentrated wastes. Drilling wastes solidified by blast furnace slag are hard and not washable and the blast furnace slag is compatible with both oil and water based drilling mud and drilled cuttings.
U.S. Pat. No. 5,213,160 entitled xe2x80x9cMethod for conversion of oil-base mud to oil mud-cementxe2x80x9d of James J. W. Nahm and Reece E. Wyant, granted on May 25th, 1993 relates to a water-in-oil emulsion drilling fluid, which can be converted into an oil mud-cement slurry for use in oil well cementing procedures.
In U.S. Patent No. 5,314,882 entitled xe2x80x9cWell drilling cuttings disposalxe2x80x9d of Arthur H. Hale, granted on Aug. 30th, 1994 well cuttings are removed by solidification by combining the cuttings with water and blast furnace slag and injection of the cuttings, water and slag into an annulus surrounding a well jacket and solidifying the cuttings, water and slag. Solidification in blast furnace slag cement is inexpensive, and the blast furnace slag is compatible with both oil and water based drilling mud.
U.S. Pat. No. 5,580,379 entitled xe2x80x9cEmulsion in blast furnace slag mud solidificationxe2x80x9d, granted on Dec. 3rd, 1996 relates to a cementous slurry prepared from drilling fluid, blast furnace slag and an emulsion comprising an oil external phase and an aqueous internal phase. After the cement slurry has been mixed and pumped into position in a bore, the emulsion breaks and the additives are released.
U.S. Pat. No. 5,476,144 entitled xe2x80x9cConversion of oil-base mud to oil-mud cementxe2x80x9d granted on Dec. 19th, 1995 relates to a drilling fluid with a water-in-oil emulsion, which can be converted into an oil mud-cement slurry for use in oil well cementing procedures.
U.S. Pat. No. 5,370,185 entitled xe2x80x9cMud solidification with slurry of Portland cement in oilxe2x80x9d, granted on Dec. 6th, 1994 relates to producing a cement slurry by combining an aqueous drilling fluid with a slurry of Portland cement in oil. The resulting composition has a particular utility in primary cementing operations for oil wells.
As it is shown by the above mentioned patents, at the moment there exist few alternatives for treating residues, and the final dispositions are all insufficient for treating the residues considering the large quantities generated through the development of the exploitation of crude oil.
During well drilling basically two types of argilliferous residues are generated. The first residues are called xe2x80x9cwater-based drill cuttingsxe2x80x9d, which are products of drilling in stable geological zones. The second residues result while drilling in unstable geological zones. To the latter materials such as oil-containing minerals, crude oil, asphalt, diesel oil, densifying additives, emulsifying agents, dispersing agents, dewatering inhibitors and viscousifier, thickening agents or liquefier, are added during well drilling, These oil-containing materials together with clays are collectively referred to as the so called xe2x80x9cinverse emulsion or oil based drill cuttingsxe2x80x9d.
In the form in which they are generated, both residues contain argilliferous materials, mainly with contents of silicium oxide, aluminum oxide and calcium oxide. These oxides are part of the oxides forming the chemical composition of the raw materials for the production of cement. Thus, the invention involves the conversion of drill cuttings and in particular well drill cuttings to cement.
In accordance with an embodiment of this invention, a process is provided for converting well drill cuttings into raw materials for cement production. The process comprises extracting limestone and clay, the crushing and pre-homogenizing the extracted limestone and clay to produce materials having a size not greater than 2.54 cm, with a maximum of 5% being retained in a 3.81 cm mesh. At this crushing and pre-homogenization stage, water-based drill cutting slug is added. The water-based cutting slug can containing particles having sizes of between 0.03 mm and 0.06 mm. The raw materials are subject to grinding, and adding corrective amounts of silica, alumina, iron, or calcium are added to form a mixture, which is dried to a moisture content of not more than 1% to obtain a powder. The powder is stored as compressed air is blown over the powder. The homogenized powder is subjected to clinker production comprising pre-heating the homogenized powder in cyclones to between 280xc2x0 C. and 350xc2x0 C., pre-calcining the pre-heated powder between 1,000xc2x0 C. and 1,100xc2x0 C. in a secondary burner, and feeding the pre-calcined powder into a rotary kiln to heat the pre-calcined powder to at least 1,450xc2x0 C. and to generate gases of 1,800xc2x0 C. to 2,000xc2x0 C. Oil-based drill cutting slug is introduced into the clinker production to thermally destruct contaminants. Cement grinding is then performed.
This method of integrating drill cuttings into the process of cement additionally provides the advantage of using the drilling sludge as raw material for the production of cement, i.e. xe2x80x9cthe use of the energy and/or the thermal destruction of the oil based sludge, which has been contaminated during well drilling.xe2x80x9d
This secure final disposition of the residues generated from well drilling by using the residues in the cement process results in avoiding or reducing ground and water contamination, recycling of argilliferous materials and thermal destruction of the sludge contaminated with hydrocarbons, thus having favorable and sustainable effects on our environment.
In many operations of gas or oil wells the drilling fluid and the materials captured by the fluid during the operation give rise to an increasing problem with respect to their handling and disposal. Superficial disposal of drilling sludge and cuttings is prohibited or undesired by regulations and environmental considerations. On the other hand, certain categories of materials produced by well drilling can be recovered as construction materials as well as various grades of sands and gravel.
An object of the present invention is the conversion of well drill cuttings into raw materials for the production of cement.
A further object of the present invention is a method for performing said conversion.
Another object of the present invention is the development of a solution for the problems of ground and water contamination in the vicinity of well drilling.
The invention has as another object the recycling and/or thermal destruction of the sludge contaminated with hydrocarbons, thus having a favorable and sustainable effect on our environment.
Additional characteristics of the invention, its nature and various advantages will become more apparent from the enclosed drawings and the following detailed description of the preferred embodiments.